Troubleshooting and Repair 3-9
Table 3-3 BIOS Beep Codes
Beep
Code
Diagnostic
Code
Description
Test Performed
3-4-2
2Dh
Screen retrace test in
progress or failure.
Over a period of time, the retrace bit
(bit0) in the appropriate CRT controller
status register (either port 3BAh or
3DAh) is read and tested. The retrace
bit should toggle from 0 to 1, then 1 to
0 within the time period.
None
2Eh
Search for video ROM in
progress.
No specific test is performed by the
system BIOS - just indicates that the
BIOS is about to jump to the
initialization code in the video option
ROM.
none
30h
Screen running with video
ROM.
No specific test is performed - just
indicates that a video option ROM was
found and believed to be operating.
none
31h
Monochrome monitor
operable.
No specific test is performed - just
indicates that the BIOS believes a
monochrome monitor is installed and is
operating.
none
32h
Color monitor (40-column)
operable.
No specific test is performed - just
indicates that the BIOS believes a color
monitor is installed and is operating.
The mode has been set to 40-column
as selected by the user in CMOS RAM.
none
33h
Color monitor (80-column)
operable.
No specific test is performed - just
indicates that the BIOS believes a color
monitor is installed and is operating.
The mode has been set to 80-column
as selected by the user in CMOS RAM.
4-2-1
34h
Timer-tick interrupt test in
progress or failure.
All interrupts expect the timer-tick
interrupt are masked off at the interrupt
controllers. If a timer-tick interrupt does
not occur during a specific time period,
an error message is displayed on the
screen. The system does not halt.
4-2-2
35h
Shutdown test in progress
or failure.
A return address is stored in 40:67h
and the processor is reset via the
keyboard controller. If a timer tick
occurs during this time period, an error
message is displayed on the screen.
Other failures are hard to detect. If
possible, the BIOS will continue with
POST, skipping the memory tests.